Hurricane HILARY

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HURRICANE HILARY DISCUSSION NUMBER 20
NWS NATIONAL HURRICANE CENTER MIAMI FL EP092011
800 PM PDT SUN SEP 25 2011
WHILE THERE HAS BEEN LITTLE MICROWAVE DATA DURING THE PAST SEVERAL
HOURS TO FOLLOW THE INNER CORE EVOLUTION...IT SEEMS THAT HILARY HAS
COMPLETED AN EYEWALL REPLACEMENT...AS THE EYE HAS GROWN A LITTLE
LARGER AND BECOME MORE DISTINCT THIS AFTERNOON. THE LATEST
OBJECTIVE AND SUBJECTIVE SATELLITE INTENSITY ESTIMATES RANGE FROM
5.5 TO 6.0 ON THE DVORAK SCALE...WHICH SUPPORT AN INTENSITY OF 110
KT. HILARY IS FORECAST TO REMAIN OVER WARM WATER AND IN A LOW
SHEAR ENVIRONMENT DURING THE NEXT 2-3 DAYS. HOWEVER...THE
HURRICANE IS LIKELY TO BEGIN INGESTING SOME DRIER...MORE STABLE AIR
THAT IS LOCATED TO ITS NORTHWEST. THIS SHOULD RESULT IN GRADUAL
WEAKENING OF THE CYCLONE DURING THE NEXT FEW DAYS. AFTER 72
HOURS...INCREASING SOUTHWESTERLY SHEAR AND COOLER SEA SURFACE
TEMPERATURES SHOULD CAUSE A FASTER RATE OF WEAKENING. THE OFFICIAL
FORECAST IS NEAR THE ICON CONSENSUS DURING THE FIRST COUPLE OF
DAYS...AND THEN IS CLOSER TO LGEM AND FLORIDA STATE
SUPERENSEMBLE...WHICH BOTH WEAKEN HILARY MORE RAPIDLY LATE IN THE
PERIOD.
HILARY HAS BEEN MOVING A LITTLE SOUTH OF DUE WEST THIS AFTERNOON.
THE HURRICANE IS FORECAST TO MOVE ON A GENERAL WESTWARD TRACK
DURING THE NEXT DAY OR SO...TO THE SOUTH OF A MID- TO UPPER-LEVEL
RIDGE THAT EXTENDS FROM NORTHERN MEXICO WESTWARD OVER THE EASTERN
PACIFIC. A MID- TO UPPER-LEVEL LOW CURRENTLY NEAR 27N133W IS
FORECAST TO MOVE EASTWARD AND WEAKEN THE WESTERN PORTION OF THE
RIDGE IN 36 TO 48 HOURS. THIS SHOULD CAUSE HILARY TO SLOW DOWN AND
TURN NORTHWARD. AFTER THAT...THE MODELS INDICATE THAT HILARY WILL
ACCELERATE GENERALLY NORTHWARD AROUND THE EASTERN SIDE OF THE
UPPER LOW. WHILE THE TRACK GUIDANCE AGREES ON THIS SCENARIO...
THERE IS A FAIR AMOUNT OF SPREAD AS TO EXACTLY WHEN HILARY TURNS
NORTHWARD...AND HOW FAST IT ACCELERATES. FOR NOW...THE NHC TRACK
REMAINS NEAR THE MIDDLE OF THE GUIDANCE ENVELOPE...BETWEEN THE
NORMALLY RELIABLE GFS AND ECMWF MODELS.
FORECAST POSITIONS AND MAX WINDS
INIT 26/0300Z 16.9N 111.3W 110 KT 125 MPH
12H 26/1200Z 16.9N 112.7W 105 KT 120 MPH
24H 27/0000Z 17.0N 114.2W 100 KT 115 MPH
36H 27/1200Z 17.2N 115.4W 95 KT 110 MPH
48H 28/0000Z 17.6N 116.3W 90 KT 105 MPH
72H 29/0000Z 19.6N 116.4W 70 KT 80 MPH
96H 30/0000Z 22.5N 116.0W 50 KT 60 MPH
120H 01/0000Z 25.5N 116.5W 30 KT 35 MPH
$$
FORECASTER BROWN
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